Following their battle against Master Mold and the Sentinels, the X-Men are given medical attention by the military, who commend the Professor and the X-Men for their assistance in destroying the menace. With Cyclops, Beast, and Iceman injured, the Professor allows them to be taken by the military paramedics to the hospital, but mentally cautions his students to protect their secret identities.

At the hospital, the doctors are unsure how to treat Iceman, who is in an unconscious delirium, prompting Professor to worry about this potentially being his first failure. Checking on the other X-Men under the pretext as a casual friend instead of their leader, the Professor overhears a doctor commenting on the fact that they could learn so much more if they knew who the young Mutant's parents are. Finding the Angel flying over a crowd of nurses checking the answering service with the mansion, the Professor is informed by Warren that his parents are coming to visit because they hadn't hear from their son in a while. The Professor calls the Worthingtons and tells them that he's on a "field trip" with his students for materials for a coming research paper. Although the Worthingtons are relieved, they insist on stopping by for a visit for only a few minutes. Concerned, not only over this, but his sense of dread, the Professor sends Warren back to the mansion to scout around.

Warren arrives at the mansion to find no trouble on the grounds, however, upon walking inside he is almost smashed by an axe which suddenly levitates out of the hand of a decorative suit of armor and smashes into the wall. Flying through the mansion, the Angel accidentally flies into a mirror and knocks himself out. His strange attacker watches, lurking in the shadows, boasting that this is the first of the X-Men he will defeat.

Back at the hospital, a doctor is almost done his examination of Cyclops, wanting to finish up by examining his eyes. Cyclops gives him a demonstration of his powerful optic blasts, explaining that he cannot control them. Finding no other problems with the young mutant, the doctor dismisses Cyclops into the Professor's care and the two walk the grounds discussing the state of the other X-Men. The Professor has lost mental contact with Angel and decides that Beast and Marvel Girl should remain at the hospital to watch over Iceman, who is still too injured to move. The Professor and Cyclops agree to return to the Mansion.

There they find no sign of Warren, and are suddenly startled when Cerebro's mutant alarm goes off. Going to investigate, the Professor examines his computer and learns that there is a super-powerful evil mutant on the premises. Before Cyclops can warn him, the Professor is suddenly wrapped up in the coils of a mental-wave distorter and sealed behind a transparent shield. Cyclops attempts to blast through it with his optic blast, but finds it redirected against him.

The lights then go out and Cyclops is attacked by their foe in the darkness. Unable to see his foe, Cyclops is easily felled in hand-to-hand combat against their unknown attacker. Back at the hospital, Beast has totally recovered from his injuries, which he shows off for Marvel Girl. Jean is concerned about the Professor and also decides to check on Bobby. When they find that Iceman is still in a coma, the two decide to venture to the mansion to see what's happened to the Professor and the others.

Arriving at the mansion, they rush into the front door and are shocked to find that the entire inside hallway has been coated with a friction-less surface. Beast suddenly slides across the room and into a specially prepared room. Jean manages to avoid the same fate by using her telekinetic powers. She is then confronted by their mystery foe, whom she recognizes immediately. Trying to keep him back with her telekinetic powers, she passes out after inhaling odorless sleep gas. Back at the hospital, the doctor caring for Iceman is called into the mutant's room because his pulse is getting weaker and he's becoming more delirious. With no other choice, the doctor decides to try a new experimental sulfa drug on Iceman and sends the nurse to go and get it.

Back at the mansion, the X-Men's mysterious attacker seals them in an enclosure of a high altitude balloon and sets it loose with the hopes that they will perish in the sky when they float up to 100,000 feet into the air. Releasing the X-Men into the air, the villain is satisfied that he has finally destroyed the X-Men. Shortly after, the Worthingtons arrive to visit their son; however, when they knock at the door they are greeted by the man who attacked the X-Men; none other than Magneto!